Wireless communication networks, such as mobile wireless telephone networks, have become increasingly prevalent. These wireless communications networks are commonly referred to as “cellular networks”, because the network infrastructure is arranged to divide the service area into a plurality of regions called “cells”. A terrestrial cellular network includes a plurality of interconnected base stations, or base nodes, that are distributed geographically at designated locations throughout the service area. Each base node includes one or more transceivers that are capable of transmitting and receiving electromagnetic signals, such as radio frequency (RF) communications signals, to and from mobile user nodes, such as wireless telephones, located within the coverage area. The communications signals include, for example, voice data that has been modulated according to a desired modulation technique and transmitted as data packets. As can be appreciated by one skilled in the art, network nodes transmit and receive data packet communications in a multiplexed format, such as time-division multiple access (TDMA) format, code-division multiple access (CDMA) format, or frequency-division multiple access (FDMA) format, which enables a single transceiver at a first node to communicate simultaneously with several other nodes in its coverage area.
In recent years, a type of mobile communications network known as an “ad-hoc” network has been developed. In this type of network, each mobile node is capable of operating as a base station or router for the other mobile nodes, thus eliminating the need for a fixed infrastructure of base stations.
More sophisticated ad-hoc networks are also being developed which, in addition to enabling mobile nodes to communicate with each other as in a conventional ad-hoc network, further enable the mobile nodes to access a fixed network and thus communicate with other mobile nodes, such as those on the public switched telephone network (PSTN), and on other networks such as the Internet. Details of these advanced types of ad-hoc networks are described in United States Patent Application 2002-0058502 entitled “Ad Hoc Peer-to-Peer Mobile Radio Access System Interfaced to the PSTN and Cellular Networks”, filed on Jun. 29, 2001, in U.S. Pat. No. 6,907,165 entitled “Time Division Protocol for an Ad-Hoc, Peer-to-Peer Radio Network Having Coordinating Channel Access to Shared Parallel Data Channels with Separate Reservation Channel”, granted on Oct. 19, 2004, and in U.S. Pat. No. 6,873,839 entitled “Prioritized-Routing for an Ad-Hoc, Peer-to-Peer, Mobile Radio Access System”, granted on Mar. 29, 2005, all assigned to the assignee of the present invention, and the entire content of each being incorporated herein by reference.
Network capacity of wireless networks is both a business and technological challenge due to the impact of increased network usage coupled with the dynamic nature of such networks. In today's conventional systems, such as single-radio wireless local area networks (WLAN), nodes typically cannot both transmit and receive at the same time. Further, traditional fundamental media access control (MAC) design of the nodes may restrict them from communicating in a full-duplex mode. These limitations in conventional nodes adversely affect the performance of multihop networks using such conventional nodes by preventing intermediate relay nodes from efficiently utilizing available resources. In particular, for example, single-radio WLAN relay nodes have to occupy an air interface twice for every packet they forward, once during the reception of the packet and again during the transmission of the packet, thereby reducing their capacity by at least half.
Several techniques exist in the art for increasing the capacity of, and overall throughput in, wireless networks. U.S. Patent Application 2004/0090924, entitled “Method and apparatus for wireless routing on a plurality of different wireless channels”, filed Nov. 4, 2003, the entire content being incorporated herein by reference, for example, relates to a wireless network in which different channels are used for conveying different types of data. Moreover, United States patent application 2003/0107998 entitled “Wireless bandwidth aggregator”, filed Jun. 12, 2003, the entire content being incorporated herein by reference, relates to a method for determining the total available bandwidth over different channels and a mechanism for splitting traffic over the channels. These two published patent applications, as well as any other documents referenced herein, are incorporated by reference.
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